Rotary frequency transformer



May 19, 1931. P. E. BUNET 1,806,386

ROTARY FREQUENCY TRANSFORIER Filed May 25 1928` Patented May 19, 179731A UNITED STATESPATENT OFFICE PAUL EMMANUEL B'UNET, Ol' VERSAILLES,v FRANCE, ASSIGNOB- 0F ONE-HALF T0 SOCIETE Acmms DE aENNnvILLrEns, or GENNEVILLIEBS, FRANCE, Aconrona;`

'non or FRANCE ROTARY FREQUENCY TRNSFOBMER y Application-111m Hay 25, 1928, Serial No. 280,588, andrin France June 2, 1927.`

My invention relates to dynamo electric machines and particularly to an improvement of special character.

As is known inthe art, a standard type of alternator is composed of an inducing member forming a certain number of poles which are alternatively north andsouth, excited by a direct current winding, and a second member in which are produced alternating electromotive `forces having a frequency corresponding to the number of poles and the rel ative speed of the two members.

The alternating electromotve forces become developed in singleor polyphase windings placed in slotsprovided `in the second member opposite the4 pole faces of the first. Asl is likewise known to-those skilled in the artthe teeth which lie between said slots tend tol produce harmonic electromotive forces whose frequency depends upon the number of slots. In general the production of these harmonicsis avoided as much as possi-ble with a view to obtaining pure elecy tromotive forces. n

I have discovered that instead lof preventing the production of these harmonic electromotive forces, I am able to Vdevelop them by suitable means inI suchfa manner that the machine in question transforms the fundamental frequency into harmonic polyphased frequencies of a high order constituting the main object of my invention. More particularly,` according to my invention, I form` slots' on the/periphery of each pole, the pitch of'said slots being equal to that .of the slots of the stator; the teeth, thus formed between the slots, are distributed in each pole in severslregions so' that in each of these regions the relativepositions ofthe teeth and slots v ofthe` rotor and statorA are identical, every Amoment. andthat inthe other regions, the

teeth and the slotsV of these two parts are deprived of a valuek equal to the pitch of the teeth divided by the number of regions. .The windings placed around teethof the pole pieces are then thekseatwof lthe polyphase electromotive forces oflhigh frequency, the number of phases corresponding to the number of regions. I can again dispose-slots,

but not in the same way `as the slots of the stator, on the pole pieces in Such a manner that in the case of two successive poles, the teeth of one pole areopposite the teeth-of the stator and the teeth of the other pole are opposite the yslotsof the stator. Windings placed around teeth of the poles are then the seat of two-phase electromotive forces with hi h frequency. In view of these means, t e total reduction of the magnetic circuit ofthe machine is kept constant every i,

Fig. 2 is a similar view illustrating a modiv fedt-wo-phase feature of my invention; and Fig. 3 is a similar View of a three-phase feature thereof.

Referring to Figure 1, the pole faces of the rotary inductor B of a standard alternator are provided with teeth b like the teeth a yin the periphery of the stator A. The inductor B is excited by windings K traversed by direct current, each of said windingsI being disposed about' a field pole` of the inductor in a manner well known in the art. l

They slots occurring between the teeth a of stator A are provided with windings dis` posed in slots f, f whose separation is equal 'y to the pole pitch of member B or to 'a kfractional pitch thereof vin a manner well known in the art. The windings f give electromotive forces of a frequency dependent upon the number of poles of member-B. f

Around th fteeth b in member B I dispose windings c which produce electromotive forces of a frequency corresponding to the number of teeth provided in the pole faces ofy v member B. l ,v

In order to eliminate considerable variation in flux due to the passage of teeth-which would induce electromotive forces in both windings K and f and thereby produce power lossesdue to the variation in flux proilucedy throughout the magnetic circuit I preferably arrangethe teeth b of successive polesof member B alternatively falling opposite notches and teeth of member A. In the s lots of the pole facesof member B which fall opposite a tooth ais provided a `second winding c1. Said windings@ and 01 are connected to- 7 gether in a manner well known in the art to' Y give two two-phase systems of high frequency. f y Instead ofproviding the slots in successive poles as'fdisclosed inconnection with Fig. 1

I may dispose the arrangement of the slots of f Y member B in the same pole thereof as shownV f in Fig.k 2 wherein the slots falling to the left and right of the axis of a'pole member in ro: tor B are displaced a distance of one-half of a tooth or V'slot successively. The windings c and 01 Vprovided in the same pole of memberB will bea source-of electromotive forces of very high frequency. The successive poles of member B may all be'the same, that is, able to be super-posed by rotation, o r similar onlyV forfacertain number, thel rest being symmetricalfand not able to be superposed by rotav`tion.; As concerns the teeth and notches, yfor "certain poles of member B, they ,may lie as shown in Fig. 2 whereas for others atthe same yinstant there may be teeth opposite teeth to thel right of the axis of the pole and Y,teeth'opposite slots to the left thereof with respect to member A.

The flux issuing from Bv distributes itself over the teeth in accordance with the respective reluctances. On the left this reluctance'V .is a minimumand on'the right it isla maximum..v It is thereforepossible to arrange the parts so'that the total reluctance vremains 'ap-ly proximately constant but that thellux is very low lon the rightl and very high on the left.

., y.When the rinductor and the stator yare given the contrary will be the case. e

In some cases I may place, lthe windings ff about' the teeth a for generating high frea relative displace-nient of one-halfof atooth,

quency 'electroinotive forces and Iv may alsoconnect suchwindings in series or in seriesparallel groups insuch' av way'as to constitute a single vhighfrequency single-phase circuit.

Finally, instead of providing two zones of slots over the pole face, there may be formed three or Vmore of themnwithsuitable angular offsetting,with collection of three-phase or higher polyphase1 electromotive forces, coinbined or not in 'siinplefsingle-phase circuits;l l Such an arrangement is shownin Fi i 3 in which I have provided three groups o slots and teeth inmemberrB. In the embodiment `the yteeth of successive groups are displaced with respect to those of member a a distance of 1/3y the distance between the axes oftwo successivekteeth of member A. rI he same any number ofvph'ases.'V n n e I Vpreferably add tothe machine suitable damping means of any type known in the art principle might obviously befcarried out forV suitable to the construction thereof. VThe-ser dampers may take two forms comprising closed magnetic circuits either surrounding the pole face as shown at G in Fig. 1 or as shown in Fig. 2, adjacent the exciting WindingKof the pole Y.

What I claim is l'. A rotary'transformer for obtaining high frequency polypliased current comprising a circumferentially and uniformly slotted sta-` tor,'aseries of field poles rotatable relative4r to the stator, an inducing winding in said stator,

an exciting winding for each of the field poles,

slots having the sainey pitch asy the stator slots lprovided inthe face iofeach ofthe said field poles, the said'slots of the field polesbeing arranged in sets, the respective lslots of the said successive setsof slots ofthe rotor'being staggered with respect to each otherbyV a dis' tance'equalto'awhole number of itches in'-Y creasedby aV fraction equal tothe pitch of the l slots divided bythe number of phases vtobe obtained, and high frequencywindings providedin the slots offeach set. f

2. A rotary transformerfor obtaining high'k frequency polyphasedr current comprising ay circumferentially and uniformlyrslotted staf` tor, a `series of field poles rotatable relative" to the stator, an inducinglwinding in ysaid stator, an exciting winding. foreach of thek field poles, slots having the sainefpitch as thestator slots provided in the face of each `of the said fieldpoles, the said slots of the field poles'being arranged in sets, in each ofA the field poles, therespectivejslots ofthe` said successive sets of slots of the rotor being staggered withfrespect toy each other by a'distan'ce Y equal' to a Vwhole number of Vpitches increasedV by a fraction equal to the pitch of the slots? divided by the numberof phases to be obtained," and high frequency windings.' provided in the slots of eachset. y f 13. A' rotary transformer for obtaining `high.

icl;

frequency polyphased currentcomprising a circumferentially and uniformly slotted'sta-sv tor, Ya series of fieldl polesrotatable.l relative iio fab

tained, and high@ requency;windings provided in theslots of each set.

In testimony whereof-'I have signedrmy A1"2`5Y name'to this. specification. v f

. 1 n PAULEMMANUEL B UNET. 

